CAMBRIDGE, Mass. — Watching the original "Star Wars" movie as a mathematically inclined 11-year-old, Helen Greiner dreamed of someday creating a robot like the heroic R2-D2. After enduring plenty of lean years chasing that elusive vision as a co-founder of iRobot Corp., Greiner can now boast a product that whirs and chirps much like the character she to this day calls her "personal hero."

The Roomba vacuum cleaner may be incapable of fixing an X-wing fighter like Luke Skywalker's trusty droid, but some 1.2 million of the disc-shaped robotic housekeepers have been sold in 25 countries in the past 2 1/2 years.

For the 37-year-old Greiner, the success of the Roomba and of iRobot's military machines validates the transformation of robots from the stuff of fantasy to practical tools.

"I think in the old days, robots had a perception of being kind of scary, and more science fiction than science fact," Greiner said in a recent interview. "These robots are on a mission, and so are we: to bring robots into the mainstream. ... We can make robots do a better job than humans in some cases."

IRobot is now the world's largest firm solely devoted to robotics, with more than 200 employees. But gaining that distinction didn't come easy.

Greiner spent long hours in the machine shop after iRobot's founding in 1990, struggling to create practical robots under continual threat of losing the financing that has kept the company going. Greiner had lucrative offers to go elsewhere, but stuck with iRobot.

"Just imagine going six and a half years, and having lots of opportunities thrown your way, and saying, 'Oh, actually I'm rather determined to make this particular activity work,'" said company co-founder Colin Angle, who met Greiner when both were freshmen at the Massachusetts Institute of Technology.

IRobot's chief military robot, a track-wheeled rover called the PackBot, has gone on thousands of missions in Iraq and Afghanistan to disarm roadside bombs by remote control and search caves and buildings.

Perhaps the most rewarding aspect of her work, Greiner said, is receiving postcards from U.S. soldiers in Iraq who feel safer because of the 150 PackBots the military has deployed.

IRobot is producing about one PackBot a day but can't keep up with the orders for a product that has yielded $50 million in government sales and research contracts.

Greiner stresses the PackBot's defensive role, but technologies that iRobot and other defense contractors are developing are expected to lead to front-line robots — from unarmed reconnaissance rovers that lead soldiers into buildings and help direct gunfire, to armed and autonomous robots that do the shooting themselves.

John Pike, director of GlobalSecurity.org, a defense consulting group in Alexandria, Va., says he expects robots to be highly effective battlefield killers by the end of the next decade.

Such prospects have raised ethics concerns, and run counter to a robots-should-not-harm-humans principle that classic science fiction author Isaac Asimov outlined in his 1950 anthology, "I, Robot" — the namesake of Greiner's company.

For her part, Greiner has said she doesn't believe robots should be empowered to decide on their own whether to take a human life.

None of iRobot's current military robots have autonomous capabilities; all are directly controlled by humans. And while iRobot is developing the PackBot's abilities to carry payloads — including the possibility of transporting weapons — none of the company's current robots is armed.

Greiner was born in London but grew up on New York's Long Island as the daughter of a businessman and nursery school teacher. When she wasn't thinking about robots, she was passionate about math, science and chess.

She enrolled at MIT with a "vision" of exploring robotics, she said, going on to earn a master's in computer science at MIT's Artificial Intelligence Lab while working on satellites at NASA's Jet Propulsion Laboratory.

When she founded iRobot with Angle and Rodney Brooks, an MIT professor who serves as the company's chief technology officer, the three would start their workdays at 10:30 a.m., take late afternoon naps on office couches then work in the machine shop until 3 a.m.

IRobot's first product, a six-legged walking device called Genghis, was designed as a tool for robotics researchers.

About six years later, iRobot began introducing its first successful military products. Then came the Roomba vacuum cleaner.

Greiner takes pride in knowing that the Roomba needed just two years on the market to reach 1 million in sales, compared with seven years for air conditioners to reach that threshold, six years for televisions and five years for VCRs.

There's a potential for even more robotic household items to be sold, with a United Nations report last year predicting that 4.1 million domestic robots — from vacuum cleaners to pool cleaners — will be in use worldwide by the end of 2007.

"I think the question will not be, 'Will you have a robot in your home?' but 'How many robots will you have in your home?'" Greiner declared.

Greiner keeps three Roombas to clean her split-level home in Wayland, a suburb about 20 miles west of Boston, where the single executive spends much of her free time reading or gardening.

She is an admitted computer game junkie, but also makes time for such outdoor pursuits as kayaking, mountain climbing and snowboarding.

Despite a fear of flying, Greiner frequently visits companies like John Deere, which is teaming up with iRobot to develop a semiautonomous battlefield vehicle, and Clorox, which developed cleaning fluid for the Scooba, a robotic floor mopper introduced last week in prototype form with plans for retail sales early next year.

Greiner, who sat down with The Associated Press after addressing a robotics conference, says she feels it's her calling to explain to the world the potential of robots.

"Today, people say, 'That's not a robot, that's a vacuum,' Or, 'That's not a robot, that's an unmanned ground vehicle in the military. But they all are robots.

"We want to make sure people understand this is a new emerging technology with a large number of areas that it can be adopted in. And at iRobot, we've taken some of the good first steps.

"But it's really the tip of the iceberg in where the industry can go. Your imagination is really the limit."

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